Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Confirm Historic Massive Flood in Climate Change

01.03.2006


Scientists from NASA and Columbia University, New York, have used computer modeling to successfully reproduce an abrupt climate change that took place 8,200 years ago. At that time, the beginning of the current warm period, climate changes were caused by a massive flood of freshwater into the North Atlantic Ocean.



This work is the first to consistently recreate the event by computer modeling, and the first time that the model results have been confirmed by comparison to the climate record, which includes such things as ice core and tree ring data.

"We only have one example of how the climate reacts to changes, the past," said Gavin A. Schmidt, a NASA Goddard Institute for Space Studies (GISS), New York, researcher and co-author on the study. "If we’re going to accurately simulate the Earth’s future, we need to be able to replicate past events. This was a real test of the model’s skill."


The study was led by Allegra LeGrande, a graduate student in the department of Earth and Environmental Sciences at Columbia University. The results appeared in the journal "Proceedings of the National Academy of Sciences" (PNAS) in Jan. 2006.

The group used an atmosphere-ocean coupled climate computer model known as "GISS Model E-R" to simulate the climate impact of a massive freshwater flood into the North Atlantic that happened about 8,200 years ago after the end of the last Ice Age. Retreating glaciers opened a route for two ancient meltwater lakes, known as Agassiz and Ojibway, to suddenly and catastrophically drain from the middle of the North American continent.

At approximately the same time, climate records show that the Earth experienced its last abrupt climate shift. Scientists believe that the massive freshwater pulse interfered with the ocean’s overturning circulation, which distributes heat around the globe. According to the record of what are known as "climate proxies", average air temperatures apparently fell as much as several degrees in some areas of the Northern Hemisphere.

Climate researchers use these proxies, chemical signals locked in minerals and ice bubbles as well as pollen and other biological indicators, as indirect measures of temperature and precipitation patterns in the distant past. Because GISS Model E-R incorporates the response of these proxies in its output, the authors of the PNAS study were able to compare their results directly to the historical record.

The researchers prodded their model with a freshwater flow equal to between 25 and 50 times the flow of the Amazon River in 12 model runs that took more than a year to complete. Although the simulations largely agreed with records from North Atlantic sediment cores and Greenland ice cores, the team’s results showed that the flood had much milder effects around the globe than many people thought.

According to the model, temperatures in the North Atlantic and Greenland showed the largest decrease, with slightly less cooling over parts of North America and Europe. The rest of the northern hemisphere, however, showed very little effect, and temperatures in the southern hemisphere remained largely unchanged. Moreover, ocean circulation, which initially dropped by half after simulated flood, appeared to rebound within 50 to 150 years.

"The flood we looked at was even larger than anything that could happen today," said LeGrande. "Still, it’s important for us to study because the real thing occurred during a period when conditions were not that much different from the present day."

The GISS climate model is also being used for the latest simulations by the Intergovernmental Panel on Climate Change (IPCC) to simulate the Earth’s present and future climate. "Hopefully, successful simulations of the past such as this will increase confidence in the validity of model projections," said Schmidt.

The study was funded by NASA, National Defense Science and Engineering Graduate Fellowship, and the National Science Foundation.

Rob Gutro | EurekAlert!
Further information:
http://www.nasa.gov/vision/earth/lookingatearth/abrupt_change.html
http://www.nasa.gov

More articles from Earth Sciences:

nachricht New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz

nachricht Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Microscopic trampoline may help create networks of quantum computers

17.07.2018 | Information Technology

In borophene, boundaries are no barrier

17.07.2018 | Materials Sciences

The role of Sodium for the Enhancement of Solar Cells

17.07.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>